Aerosol cans which are disposed in trash pose serious environmental pollution problems in that they contain propellants, solvents and residual chemicals. The current common propellants range from propane, isobutane, butane, (hydrocarbon gases) and CO.sub.2 to fluorocarbons (freons). Fluorocarbons have been proven to be a major contributing factor in the deterioration of the ozone layer in the upper atmosphere allowing a greater percentage of ultraviolet rays to reach the earth's surface resulting in increased skin cancer potential. Hydrocarbon gases and CO.sub.2 are contributing to a dangerous rise of global average temperatures (otherwise known as the "Greenhouse Effect"). Fluorocarbons are being banned in many countries, but are still produced in others, are still in stock, or are continuing to be disposed as consumers gradually use them or the disposed cans deteriorate.
The chemicals contained in the cans range from non-biodegradable insecticides, paints and varnishes, caustic chemicals for cleaning compositions, antiseptics, hair spray, and deodorant, to name a few. Typically, the insecticides, paints and varnishes contain petroleum-base solvents or carrier liquids.
Further, the inability to recycle the cans represents a serious waste of the various raw materials, including the hydrocarbon/CO.sub.2 or fluorocarbon propellants, the solvents, the chemicals, and the can materials. These latter include aluminum or tin can materials, the balls used for mixing the contents, and various plastic parts. One of the most important plastic parts involved is high density polyethylene or polypropylene, which is currently the preferred plastic that is used for the dip tube in conjunction with the petroleum solvent carriers.
As the cans gradually corrode in landfills, they release the propellants into the atmosphere, and the solvents and waste chemicals therein into the water table. The numbers are staggering. In the US alone, during only three years 1986-1988, the number of aerosol cans in all product categories produced was in excess of 8.145 billion cans, a majority of which will eventually wind up to deteriorate slowly over the years in landfills, releasing the propellant gas and seep into the atmosphere, and the waste chemicals and solvents into our water tables. Assuming all of the cans are used but understanding no can be completely emptied, and assuming therefore that only 6 grams of chemical products (chemicals plus solvents) are left in each (incompletely) "emptied" can (not including 1-3 grams of propellant necessarily left in the can), for the years 1981-1988 inclusive, this waste amounts to 259,821,000 pounds, or 129,935,000 liters, or 34,329,000 gallons of waste, the vast majority of which is believed to be improperly disposed in land fill. It is this waste (chemicals, solvents and propellants) that will be discharged over the next 5-100 years as the cans deteriorate.
The recycle value of the cans is significant. For the 3 years 1986-1988 in the US, some 2,854,000,000 cans fall in the personal use category of which almost all are aluminum. If only 10% of all 8.145 billion cans are aluminum and they are on the average a small 9 ounce can (a conservative figure), then on the average there are 13 cans/per pound. The aluminum content amounts to 62,660,000 pounds with a recycle value of $56,400,000 in today's market. For every can recycled, there is also energy of production saved, and a reduction in pollution (e.g. reduction in coal, oil or gas burned to produce electricity to electrolytically refine bauxite to aluminum, and then to roll sheet and form cans).
Empty containers, including spent aerosol cans, which typically contain 3% or more of the original liquid (chemical), are considered "hazardous wastes" and may be disposed only in accord with federal, state, or local codes and/or regulations. For example, in California, under the Tanner bill, disposal of household hazardous wastes (in which spent aerosol cans are included) will be closely regulated by counties and cities as part of the California State Hazardous Management Plan. By Nov. 1, 1989, counties and cities must submit a plan for safe disposal of hazardous wastes to the state. States have in place or are looking to mandate segregation and curbside collection of such hazardous wastes. Curently, spent aerosol cans are being landfilled, but the Federal Hazardous Substances Waste Act calls for phase-out of disposal of all untreated hazardous wasted in landfills by 1992. If that deadline to ban landfill disposal of cans is met, then because of their "time bomb" nature (delayed release of propellants to the atmosphere and leakage of chemicals of solvents into the soil and/or water table), aerosol can production would drop drastically or require expensive treatment or incineration. Incineration poses other problems, not the least of which are increased CO.sub.2 emissions, and the requirement to scrub the incinerator off-gasses.
Additionally, there are problems associated with filling the aerosol cans. The solvents used in combination with some chemicals under pressure may cause differential swelling between the plastic dip tubes and the collar in the cap member of the aerosol can that receives and holds the dip tube. This results in the all too common occurrence of a disconnected dip tube, which can sometimes be remedied by operating the aerosol can in the upside down position. But usually the aerosol can is rendered useless by a disconnected dip tube as consumers will not buy such cans.
Various U.S. Pat. No., such as: 3,835,768 (Kidson, 1974); U.S. Pat. No. 4,133,261 (Belfils, 1979); and U.S. Pat. No. 4,418,460 (Ruth, 1983), teach recycling non-aerosol cans by total destruction of the can by a process involving puncturing the side wall of one can at a time. This process wastes energy in crushing the cans and then reforming them by smelting, sheet metal rolling and forming the sheet into new usable cans.
Many of the propellants used in aerosol cans are explosive or flammable, and therefore the process of disposal, emptying and recovery of the contents of rejected or partially used aerosol cans involve many safety considerations. U.S. Pat. No. 4,349,054 (Chipman et al., 1982); U.S. Pat. No. 4,407,341 (Feldt et al., 1983); U.S. Pat. No. 4,459,906 (Cound I, 1984); and U.S. Pat. No. 4,526,097 (Cound II, 1985) teach various multi-stage processes for the safe transfer of contents, disposal or recycling of aerosol cans. These patents employ an apparatus having an enclosed chamber wherein the aerosol container is fixedly retained and the side wall punctured. Next, the contents are discharged into a receiving area to be recycled, and the ruined can is then cleaned and compacted (crushed). Again, these patents do not permit reuse of the original aerosol containers, as the methods and apparatus used for reclaiming the contents effectively destroy the mechanical integrity of the can.
Most cans today fall generally into one of three classes:
A) a two-part construction, such as a spun aluminum soft drink can having a body (base and side walls) with a lid attached by a rolled flange;
B) a three-part construction, where both top and bottom portions are attached to a drawn or sheet metal body by rolled flanges; or,
C) a four-part construction, e.g. a typical aerosol can having a drawn or seamed sheet metal body (tubular side wall) attached to a top and bottom portion by a rolled flange, wherein the top is apertured to receive a central cap containing the valve and dip tube assembly.
U.S. Pat. No. 2,423,708 (Keogh et al., 1947) teaches salvaging metal cans by cutting off the top end closure of a single-closure type can. After the can is cleaned, it is subjected to further drawing action, which thins the walls and bottom portion while restoring the length of the can body to its original height. A new closure is then installed on the thinner-walled can. This process requires a two-part can, that is, a can having a body (base and side walls) drawn from a metal blank, and the lid is secured at the open end. This method is not efficient since the recycling process involves the added cost of a secondary drawing, and is limited to one or two applications at most before the walls of the can are too thin for reuse.
U.S. Pat. No. 3,473,499 (Bishop, 1967) and U.S. Pat. No. 3,618,429 (Froeliger, 1969) disclose methods to remove a flanged metal container top by applying a downward axial force to the top to bow it sufficient to deformingly unseal the rolled flanges.
Bishop U.S. Pat. No. 3,473,499 teaches a method to open a can top wherein two half-cylindrical body parts are brought together around a can so that the outwardly directed flange or seam of the can overlaps the end faces of the body parts, the end faces being frusto-conical. There is also provided a plunger that is downwardly and axially engaged to the top of the can, thereby causing the flange or seam to be forced against the frusto-conical end faces causing the flange or seam to be unrolled or stretched outwardly releasing itself from the side wall of the can. This method tends to destroy the can body lip so that reuse of the can is not feasible.
Froeliger U.S. Pat. No. 3,618,429 teaches a similar method to remove the lid of a drum wherein a plunger having a blunt surface is engaged with the lid of a drum causing deformation to the lid as the plunger moves axially downward. The plunger end also includes radially outward extending jaws that are for grasping the bead of the lid while the plunger deforms the lid material causing the bead of the lid to unroll off the can body lip. The drum is usually reusable in this method.
However the methods taught in both Bishop and Froeliger are designed to apply only to drum-type containers (a container wherein a flat lid extends to the outer diameter of the container) and will not work on aerosol cans due to the fact that the cap containing the aerosol valve and center riser portion is inset and smaller than the can diameter, and the can top is usually a raised dome. In addition, these methods are intended for non-pressurized containers and are extremely unsafe for aerosol cans which are typically under high pressures (100-150 psi). More over, aerosol cans, by the nature of their contents (solvents, chemicals, propellants, etc.), are dangerously flammable and explosive if punctured or opened improperly.
It is also known to use pincer-like tools in combination with a plunger device to remove closures of containers. U.S. Pat. No. 2,612,065 (Packer et al., 1952) and U.S. Pat. No. 2,732,741 (Muller-strobel, 1956) teach the use of side grippers or pincers that engage the perimeter of either a crown cap or insertable plug-type metal covered rubber container plug after which a plunger is actuated downward, whereby the cap or plug is released from the container. One of the two side grippers disclosed in Packer has an added cam disposed to force the side gripper up and outward upon actuation of the plunger thereby deforming the affected part of the crown cap. This is simply a mechanical crown-type bottle cap opener. In Muller-Strobel side pincers apply a radially inward force to the sides of the metal-foil covered rubber plug above the bottle opening. A downward plunger movement prevents the rubber from buldging upwardly. The plug can them be pulled out of the bottle. These methods work well for the bottle-type of enclosures for which they were designed, but they are not suited to remove the top cap from an inset cap type metal aerosol container without damaging the container.
Accordingly, there is a need in the art for an apparatus and method to safely remove the inset center cap member of mis-filled, partially empty and spent aerosol cans without damaging the can or dome top itself so the can may be reused while reclaiming the residual contents, and separating the different materials in order to be recycled and prevent pollution of the environment. There is a need for a cost-effective method and apparatus for reclamation, cleaning and re-labeling of the containers, and recycling of the expensive plastic dip tube and other can parts, including the can body.